Nontwisting, nontoppling tackle block for boat davits



April 22 1924. 1,491,751

D. C. MCMILLAN NONTWISTING, NONTOPPLING TCKLE BLOCK FOR BOAT DAVITS Filed March 25 1.922

Patented Apr. 22, 1924.

DONALD C. MCMILLAN, OF BROOKLYN, NEW YORK.

NONTWISTING, NONTOIPPLING TACKLYE BLOCK FOR BOAT DAVLTS.

Application filed VMarch 25, 1922. Serial No. 546,576.

To all rwhom t may concern.'

vBeit known that I, DONALD C. MCMIL- LAN, a citizen of the Unitedy States, and resident of the borough of Brooklyn, county of Kings, city and State of New York, have invented new and useful Improvements in Nontwisting, Nontoppling Tackle Blocks for Boat Davits, of which the following is the specification.

The device, the subject of this invention is a tackle block intended for all general service, but so designed as to operate with a higher degree of eiiiciency than the ordinary block.

Because of the shape of my blocks, it will appear quite obvious that they may be worked closely together. This is important in the handling of nested life boats, where but little drift is usually allowed, the purpose being to retain the davits or stanchions at a minimum height.

Another important feature to be found in my block is the provisions upon the lower block which prevent the toppling, twisting or fouling of the block.

Another important object is to so construct the blocks that a maximum strength may be obtained from a minimum size and weight.

Other objects and features and the details of construction will be fully set forth as the specification progresses and the accompanying drawing should be referred to for a complete understanding of the specifica tion which follows In the drawing p Fig. 1, is a perspective view of a boat and davits.

Fig. 2, is a central, vertical section through the upper block, certain parts being in elevation.

Fig. 3, is a central, vertical section of the lower block, certain parts being in elevation.

Fig. 4 is a perspective view of a pair of blocks in operative position.

Fig. 5, is a vperspective view of the guides.

Similar reference numerals indicate like parts in all the figures where they appear.

As it is customary for tackle blocks to act in pairs, I have shown and will describe a pair of blocks constructed accordL ing to my invention.

The upper block is provided with a shell or casing 10, which may be of wood or any other suitable material, though in the block shown, the wooden construction is preferred. This casing or shell is formed of a suitable number of parts to provide mortises or passages wherein the sheaves are arranged, and in the construction I show three such mortises, indicated at 11, 12 and 13, wherein are arranged the sheaves 14, 15 and 16.

These sheaves are provided with suitable bearings, such as, roller bearings as shown at 1f? in Fig. 3 or bronze self lubricating bearings or bearings of any other preferred type and are rotatably supported upon a common pin or shaft 18, which extends through the casing.

At one end of the pin 18, I provide an eye 19, as shown and at the other end, a nut 20 to retain the pin in place.

I call particular attention to the straps shown in detail in Fig. 2. These straps extend quite through the casing l0 and are of a large U-fshape, the arms of the strap 21 extending outward, are provided with perforations through which the pin 18 passes. The arms of the strap 22 also receive the pin 18. Both of the strapsare provided with loops or return bend-s, through which may be passed the pin 23 of the shackle 24 and it will be noted from a study of this construction that the casing 10 carries no load, its only functions are to incase the sheaves,

to act as a guide for the falls and to guardthe sheaves and falls against injury or entanglement. y

Pins as shown by the dotted lines'25 and V26 secure the several parts of the casing together and to the straps or U-shape members 21 and 22.

As previously stated, itis my desire that the blocks operate in close proximity to each other and to make this possible it will be noted that the casing for each block has a iattened portion and in the upper block, while the upper part of the casing adjacent the shackle 24 is rounded or shaped in the customary manner, the block kis actually triangular in end elevation, the base of the triangle being next adjacent to the lower block and the straps and shackle being arranged at the apex of the triangle for the purpose of symmetry and to prevent the block catching upon abutting surfaces, the points of contact of adjacent sides of the triangle are rounded. Y

y To further reduce the necessary separa-V tion between blocks of a pair, the becket or vSi) secured end 27 of the falls 28 is made fast to the eye 19, which it will be noted is at the side of the block.

rIhe second block of the pair shown in section in. Fig. 3, is the travelling or lower block and in shape and size corresponds to the upper block previously described.

This block may have any number of sheaves, but I have shown three to accommodate the tackle arrangement shown which is the tackle usu ally employed with life boat davits. These sheaves 29, 30 and 31 are rotatable upon a pin 32, which is provided with an eye 35 and a nut 34 for retaining the pin in position.

The straps 36 and 37 are formed integral Y with'y a plate member 38, wherein is secured a swivel-eye 39, to which a boat releasing device may be secured.

Inthe eye 35 of the pin 32, I may arrange a shackle 40, or thimble for a purpose that shall appear later.

I call particular attention to the guide plates 4-1 and 42 arranged one at each side ot the block and having extended portions fitting into the mortises of the block. These plates guide the lfalls and prevent capsizing or toppling of the block. j

lVhen these blocks are employed as a part ot the davit equipment, as shown, a cable or spar 43 may besecured to oppositely arranged eyes 19, or shackles 40 and will further assist in retaining the blocks against twisting during operation.

It is obvious that any other litting desired may be substituted where eyes or shackles are shown, that blocks may be constructed with any number of sheaves and that other modications may be made within the scope of the appended claims without departing trom the principle or sacrificing the advantages ot' the invention. Y Y

I prefer the whole as shown and described, however, and desire to adhere to shape and general construction as the best means for accomplishing the purposes sought. Y

Having carefully and fully describedmy invention what I claim is 1. A pair of tackle blocks adapted to'operate in close proximity, said tackle blocks being of approximate triangular shape with the bases of the triangles next adjacent to y each other, an eye at one side of one said block for the reception of the becket and nontilting means upon the other said block and adjacent to the base of the triangleV said means comprising guides projecting into the mortises of the block.

2. A pairof tackle blocks adapted to operate closely adjacent, both said blocks being approximately triangular in elevation, appl-urality of straps passing through one said block, aV pin passing through said straps supporting the sheaves therein and an eye on said pin for the reception of the becket, a plurality of straps passing through the other said block, a pin passing through said straps to support the sheaves in said block and an eye on said pin to receive a cable to prevent the twisting ofsaid block.

Signed at ythe city, county and State of- New York, this 15th day of March, 1922.

DONALDk C. MCMILLAN. 

